Elastocapillarity: Adhesion and Wetting in Soft Polymeric Systems

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• 作者：Zhen Cao ; Mark J. Stevens ; Andrey V. Dobrynin
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：September 23, 2014
• 年：2014
• 卷：47
• 期：18
• 页码：6515-6521
• 全文大小：378K
• ISSN：1520-5835

文摘

We have developed a generalized model of particle-substrate interactions describing both adhesion and wetting behavior. Using a combination of the molecular dynamics simulations and scaling analysis we have shown that the crossover between adhesion and wetting-like behavior for a particle with size R_p and shear modulus G_p interacting with a substrate of shear modulus G_s is determined by the dimensionless parameter 尾 鈭?纬*(G* R_p)^鈭?/3W^鈥?/3, where G* = G_pG_s/(G_p + G_s) is the effective shear modulus, W is the work of adhesion between particle and substrate, and 纬* = Wg_r + 纬_p(1鈥?g_r) + 纬_spg_r² is the effective surface tension of the particle/substrate system with 纬_p and 纬_s being surface tensions of particle and substrate, 纬_sp 鈭?surface tension of the particle-substrate interface, and g_r = G_p/(G_p + G_s). This parameter 尾 is proportional to the ratio of elastocapillary length 纬*/G* and contact radius a, 尾 鈭?纬*/G*a. In the limit of small values of the parameter 尾 < 1, when the contact radius a is larger than the elastocapillary length 纬*/G*, our model reproduces Johnson, Kendall, and Roberts results for particle adhesion on elastic substrates (adhesion regime). However, in the opposite limit, 尾 > 1 (a < 纬*/G*), the capillary forces play a dominant role and determine particle-substrate interactions (wetting regime). Model predictions are in a very good agreement with simulation and experimental results.